Cementing jig



June 12, 1945. p. F. PRESTON CEMENTING J IG Filed March 12, 1942 e Sheets-Sheet 1 INVENTOR ATTORNEY June 1945- I P. F. PREQSTCI'N 77,962

CEMENTING JIG Filed March 12, 1942 s Sheets-Sheet 2 ATTOR N EY JupelZ, 1945. v P. F. PRESTON 2,377,9 2

CEMENTING JIG Filed March 12, 1942 6 Sheets-Sheet 3 ATTQR NEY 1 F. PRESTQN CEMENTING JIG June 12, 1945.

Filed March 12, 1942 .6 Sheets-Sheet 4 jazz P5961 012 I-INVENTOR ATTORNEY 3121mm; 2945. F; PRESTON 2,3779% CEMENTING J 16 6 Sheets-Sheet 5 Filed March 12, 1942 jQll/EPPQJfO I? INVENTOR ATTORNEY June 12,1945

P. F. PRESTON CEMENTING JIG Filed March 12. 1942 6 Sheets-Sheet 6 BY .Mm

ATTORNEY Patented June 12, 1945 UNITEDISTATES PATENT OFFICE CEMENTING JIG Paul F. Preston, Newark,.N. J.,' asslgnor to E. I. du Pont de Nemours & Company, Wilmington, Del a corporation of Delaware Application March 12, 1942, Serial No. 434,331

Claims. (Cl. 154-1) appearance as well as strength, it is required that the cemented joints be homogeneous and free from bubbles. To achieve a uniform joint any device for applying pressure in the cementing operation must ,eiiect a substantially equal distribution of pressure along the curvature of the joint. It must further be such as will not mar the cemented parts and, for speed in production, will permit of rapid manipulation.

It is an object of the present invention to provide a jig for applying and maintaining substantially uniform pressure upon curved structures while cementing them together.- More particue larly, it is an object to, provide a pressure jig for forming continuous, bubble-free'cemented joints between strengthening ribs and transparent plastic airplane structures. A further object is to Fig. 3 is a diagrammatic perspective view of 'the jig shown in Figs. 1 and 2;

Fig. 4 is a perspective view of a cementing ji according to another embodiment of the invention';

Fig. 5 is a perspective view of a frame cooperating with the jig shown in Fig. 4; and

Figs. 6-A, 6B, and 6--C illustrate, in perspective, the operative relation of the jig shown in Fig. 4, and the frame shown in Fig. 5, to arib and airplane shell to be cojoined.

Referring to Figs. 1, 2, 2 -A and 3, a completely formed shell 2 of organic plastic material is placed upon the bench 4, within the stops 3, ar-

furnish an easily manipulated jig for forming I satisfactory joints between curved mating organic plastic parts without marring the material.

Other objects will be apparent from the descripv fects the lateral and forward displacement of a pair of expanding members in such a manner that the pressure causingthe advancement is distributed substantially uniformly along the curved length of the expanding members.

In order that the invention may be more readi- 1y understood, reference is made to the accompanying drawings in which: Fig. 1 is a plan view of a cementing jig, according to one embodiment of the invention, in operation in the cementing of a rib to one end of half an airplane nose piece;

Fig. 2 isa front elevational view of the jig shown in Fig- 1;

Fig. 2A is a section along the line A-,-A in Fi 2; V

ranged along a curve corresponding to the bottom of the shell and securely fastened to the bench. A rib I, of similar material, preferably bent and machined to shape and softened with solvent or coated with adhesive, is located against the inside of the lower edge of the shell 2. Expanding members 5, each having one edge conforming to the curvature of the joint, are placed in position, free to move upon the surface of the bench, and the wedge B, constituting the central pressure element, is inserted in the V-shaped space between the two members. Pressure applied to the wedge t by means of thumb screws l, engaged by threads with brace 8', which latter is fastened to bench, advances the wedge 8 in a direction median to the curve of the joint and forces the two expanding members 5 forwardly and outwardly, so that the pressure is transmitted to the cemented surfaces in directions everywhere normal to the joint.

It is preferred that the stops it, which together constitute a negative form, be constructed of transparent material, so that the Joint will be visible from without during the cementing operation. Organic plastic material is ideally suited to this use. All stops may be arranged exactly on the curve, as shown, or alternate stops may be slightly recessed to permit the driving of a wooden wedge between the stop and the shell to repair fortuitous local pressure deficiencies due to lrregularitiesin the shape of the cemented parts. For clarity in the drawings only a few stops 3 are shown but in actual fact many more would normally be used.

Wood is the favored material for the expanding members 6 and the wedge 8, although other materials may be used. The broad and of the wedge '6 may be provided with a metal plate 9,

applying uniform pressure without mar-ring to curved mating parts during cementing and for maintaining that pressure as long as is required for the proper strengthening of the bond. It permits the formation of strong bubble-free bonds between curved organic plastic structures. A suitably shaped Jig may be used in cementing a rib to any part of a curved object. If desired, a series of jigs properly positioned may be employed to secure a series of ribs to a shell or simi= lar structure simultaneously at different levels.

Referring to Figs. 4, and 8-A, 6-H, and 6'C, another-embodiment of the invention is illustrated. The pressure iig comprises expands ing members It actuated by threaded central pressure element It engaging the threaded core of collarv it which is rigidly attached to cross piece ll. The cross piece II, which consists of a channel iron, is provided on each end with ears 20 and notches 22. The central pressure element It is furnished at the top with a wheel it keyed thereto or otherwise prevented from independent rotation. Only the upper portion of the central element It need be threaded. The lower portion is equipped with alternate series of fixed collars 24, burnished or shrunken thereon, loose collars 25, washers 28, and springs 21. The loose collars 25, free to move up and down the centralpressure element It except as restricted by the fixed collars 24 and springs 21, areattaohed to one end of connecting links II by pairs oi metal straps 25-a and cooperating bolts 25-1). The metal straps 25-0 bind tightly on the loose 001- lars 25 and remain in fixed relation thereto. At the opposite end each link It is pivotally attached to a lug 28 fastened to the inner surfaces of the expanding members II. The outer surfaces of the expanding members it bear a groove it which mates with the plastic rib I2 (see Fig. 6), in the cementing operation.

The expanding members I! are attached to the cross piece I! by L-shaped brackets 29 provided with slotted openings 20 and tl-a. For clarity of illustration the cross piece I! is shown in Fig. 4 as slightly separated from the expanding member IE but it will be understood that bolts fixed in the cross piece II will be passed through the slotted openings 20 in the brackets 22 just as the bolts' 30-h fixed in the expanding members It pass through the slotted openings "-a (see the right hand member II in Fig. 4). By this arrangement the members II are permitted 9. limited movement both toward and from the cross piece I! and, also, along the longitudinal axis of the cross piece At their lower-ends the members it are preferably Joined by a slotted bar It cooperating with pins 32 carried by the members It; this construction permits limited relative lateral movement of the members It in a plane including the two.

The formed shell II is first introduced into fixture H (see Figs. 5 and 6). Rib l2, already curved and machined to shape, and softened or coated with cement, is then inserted in the shell tions of the various parts of the pressure ii: are carefully adjusted so that the pressure of the central screw element It is transmitted everywhere substantiall normal to the curvature of the Joint.

Washers 26 and springs 21 serve to hold loose collars 25, inposition against fixed collars 28..

They may be replaced by another set of collars rigidly fixed upon thescrew element ll lust.

below the loose collars 28.

In either embodiment of the invention, the rib i preferably shaped prior to being introduced into the shell. The rib may, however, be taken in a crudely shaped or completely unshaped state and, having been softened by heat or solvent, forced into the proper configuration by means of the pressure jig. To this use the type of M8 shown in Figs. 4 and 6-A is particularly adapted, for the groove in the expanding members ll mates with the rib and holds it from lateral displacement.

By suitable modifications of either type of jig,

. strengthening parts can be cemented to an exit and adjusted to the desired position.' The pressure jig is next lowered into place, with the ears 2c slipping over diametrically opposed portions 2! of the fixture. Clamps 22 engage notches 23 at theends of the cross piece ll firmly securing the jig to the frame. a

Progresslvely advancing the screw element It in collar I 9 lowers that portion of the element to which the connecting rods are attached. Fixed collars 24 bear upon loose collars 2i, forcing the ccnnectlng'links II and the expanding members It downward and outward. The relative positernal'surface of a shell with equal facility.

Two specific embodiments of the invention have been illustrated in the drawings but the invention is not limitedto these specific forms and more broadly resides in an apparatus for cementing together a pair of curved mating parts of plastic, material which apparatus includes a limiting fixture having an inner edge conforming to the curvature of the outer mating part along the line of the joint to be made with the inner mating part, a pair of expanding members each having an outer edge conforming to the curveture of the inner mating part along the line of the joint, together with a central pressure element adapted to displace the expanding members laterally and forwardly to apply, in cooperation with the limiting fixture, pressure substantially uniformly along the line of the joint.

It will be understood that the apparatus of the present invention is perfectly well adapted for cementing together mating parts where the line of the joint includes straight portions in the curve and it is intended. that the term ,"curved mating parts" shall include curves of this type as well as continuous curves.

The herein disclosed apparatus is suitable for cementing parts of any plastic material and is especially well adapted for cementing parts of advantages of the invention are especially apparent in cementing operations involving airplane structures of transparent organic plastic material where the requirements of high optical quality, adequate strength, and trim appearance must be made on diillcult shapes of easily marred material.

As many apparently widely different embodl ments of. this invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended c I claim:

1. An apparatus for cementing together a pair of curved mating parts of plastic material which apparatus comprises a limiting fixture having an inner edge conforming to the curvature of the outer mating part along the line of the Joint to be made with the inner mating part, and a jig including a cross-piece, a'palr of rigid expandin members slidably connected to each other at one end to permit lateral movement relative to each other in a plane including both, and slidably connected at the opposite ends to spaced points along said cross piece to permit a combined lateral movement relative to each aother in said plane including both and a forward movement with respect to the longitudinal axis of said cross outer mating part along the line of the Joint to be made with the inner mating part, and a jig including a cross piece, a pair of rigid expanding members slidablyconnected to each other at one end to permit lateral movement relative to each other in a plane including both, and slidably connected at the opposite ends to spaced points along said cross piece to permit a combined lateral movement relative to each other in said plane including bothand a forward movement with respect to the center of said cross piece, a screw member threadably mounted in said cross piece and. extending therefrom in said plane including said expanding members toward the point of connection of the ends of said expanding members to each other, a spaced series of pairs of links, each pair being connected to said screw member on-opposite sides thereof adjacent said expanding members and each link of said pair being pivotally connected to its adjacent expanding member, and means for turning said screw member in its threaded mounting in said cross piece to displace through said links said expanding members laterally and forwardly to apply, in cooperation with said limiting fixture, pressure substantially uniformly along the line of said joint. l

3, An apparatus for cementing together a pair of curved mating parts of plastic material which apparatus comprises a limiting fixture having an inner edge conforming to the curvature of the outer mating part along the line of the joint to be made with the inner mating part, and a jig including a cross piece, a pair of rigid expanding members slidably connected to each other at one end to permit lateral movement relative to each other in a plane including both, and slidably connected at the opposite ends to spaced points along said cross piece to permit a combined lat-.

eral movement relative to each other in said plane including both and a forward movement with respect to the center of said cross piece, a screw member threadably mounted in said cross piece and extending therefrom in said plane including said expanding members toward the point of connection of the ends of said expanding members to each other, a spaced series of pairs of links, each pair being connected to said screw member on opposite sides thereof adjacent said expanding members and each link of said pair being pivotallyconnected to its adjacent expanding member at a point more distant from said cross-member than the point of attachment of said link to said screw member, and a wheel mounted on said screw member for turning said screw member in its threaded mounting in said cross piece to displace through said links said expanding members laterall and forwardly to apply, in cooperation with said limiting fixture,

- pressure substantially uniformly along the line of said Joint.

4. An apparatus for cementing together a pair of curved mating parts of plastic material which apparatus comprises a limiting fixture having an inner edge conforming to the curvature of the outer mating part along the lineof the joint to be made with the inner mating part, a pair of rigid expanding members each having an outer edge extending approximately half way along the line of said joint, said members being so positioned and shaped that said outer edges present substantially a continuous face conforming to the curvature of the inner mating part along the line of said joint and abutting against said inner mating part along the line of said joint, and a central pressure element adapted to displace said expanding members laterally and forwardly to apply, in combination with said limiting fixture, pressure substantially uniformly along the line of said joint.

5. An apparatus for cementing together a pair of curved mating parts of plastic material which apparatus comprises a plurality of fixed stops arranged in a curve conforming to the curvature of the outer mating part along the line of the joint to be made with the inner mating part, a pair of rigid expanding members each having an outer edge extending approximately half way along the line of said joint, said members being so positioned and shaped that said outer edges present a. substantially continuous face conforming to the curvature of the inner mating part along the line of said joint and abutting against said inner mating part along the line of said joint and a wedge positioned between said pair of expanding members and adapted to be driven forward to displace said expanding members laterally and forwardly to apply, in cooperation with said fixed stops, pressure substantially uniformly along the line of said joint.

I PAUL F. PRESTON. 

